Abstract:
Echinochloa species are the most problematic grass weeds in rice fields worldwide. The species of this
genus have high intra- and interspecific variability, with many ecotypes. Based on this, the study was
conducted to characterize the morphology and phenology of Bangladesh Echinochloa accessions and
evaluate their herbicide sensitivity. The results showed a distinct variability of the growth characteristics
among Echinochloa ecotypes. The four Echinochloa accessions, designated Echinochloa crus-galli
ecotypes A, B, C, and D, were discovered in the various rice-growing regions of Bangladesh. The same
ecotypes were treated with pre-and post-emergence herbicides in pot culture and the puddle and dry
sowing conditions to determine the herbicide sensitivity. Among the pre-emergence herbicides, all except
butachlor in dry sowing conditions and pyrazosulfuron ethyl in both puddle and dry sowing conditions
were effective against ecotypes of Echinochloa detected. Bispyribac sodium and metamifop were effective
in both the four-leaf and eight-leaf stages of E. crus-galli ecotype D. In contrast, fenoxaprop–p–ethyl was
effective at the four-leaf stage. E. crus-galli ecotype B was effectively controlled by quizalofop-p-ethyl
when sprayed at the eight-leaf stage and fenoxaprop–p–ethyl at the four-leaf stage. E. crus-galli ecotype C
was less susceptible to all the herbicides. However, quizalofop-p-ethyl and fenoxaprop-p-ethyl, although
effective at the four-leaf stage in reducing the weed persistence index (WPI). This information helps make
weed management decisions and is informative in understanding the speciation and adaptation of weedy
Echinochloa species.
